In the past decades, a number of anti-cancer drugs have been discovered from natural products, which represent an attractive source for identification of novel anti-cancer agents [1]. Ginsenoside Rh2 is one of the major ginsenosides of ginseng roots, and previous studies showed that Rh2 could markedly reduce cell proliferation, cause cell cycle arrest and induce differentiation and apoptosis in variety types of cancer cells, of which a number of molecular pathways and proteins are participated in its anti-cancer action. Also, the cytotoxicity of Rh2 ginsenoside against tumor cells showed in different potencies with their stereochemical properties, i.e. 20(R)-Rh2 and 20(S)-Rh2. 20(S)-Rh2 demonstrated potent cytotoxicity against several tumor cell lines, with IC50 value of 22-50 μM; while 20(R)-Rh2 is a selective osteoclastgenesis inhibitor but without any cell cytotoxicity [2]. Previous studies of the inventors indicated that 20(S)-Rh2 exhibited cytotoxicity with IC50 value of 45-65 μM in a panel of 7 tumor cell lines and also in the human normal lung fibroblasts; while 20(R)-Rh2 only displayed poor solubility without cytotoxic effect up to 100 μM in cell culture. In addition, the inventors have previously demonstrated that the stereochemistry of the hydroxyl group at C-20 of Rh2 ginsenoside plays important roles in anti-tumor activity in vitro [3]. Beside, a recent report revealed that poor intestinal absorption of Rh2 was due to the poor permeability and ABC-transporter-mediated efflux; while the significant stereo-selective absorption of 20(R) isomer exhibited lower absorption profiles possibly due to more potent efflux [4].